The prospect certainly was not a bright one. The door was fast locked. Escape from the windows seemed impracticable. This apparently exhausted the avenues of escape that were open to the dissatisfied prisoner. But accidentally Jack made an important discovery.

There was a full-length portrait in the room. Jack chanced to rest his hand against it, when he must unconsciously have touched some secret spring, for a secret door opened, dividing the picture in two parts, and, to our hero's unbounded astonishment, he saw before him a small spiral staircase leading down into the darkness.

"This is a queer old house!" thought Jack. "I wonder where those stairs go to. I've a great mind to explore."

There was not much chance of detection, he reflected, as it would be three hours before his next meal would be brought him. He left the door open, therefore, and began slowly and cautiously to go down the staircase. It seemed a long one, longer than was necessary to connect two floors. Boldly Jack kept on till he reached the bottom.

"Where am I?" thought our hero. "I must be down as low as the cellar."

While this thought passed through his mind, voices suddenly struck upon his ear. He had accustomed himself now to the darkness, and ascertained that there was a crevice through which he could look in the direction from which the sounds proceeded. Applying his eye, he could distinguish a small cellar apartment, in the middle of which was a printing press, and work was evidently going on. He could distinguish three persons. Two were in their shirt sleeves, bending over an engraver's bench. Beside them, and apparently superintending their work, was the old man whom Jack knew as Dr. Robinson.

He applied his ear to the crevice, and heard these words:

"This lot is rather better than the last, Jones. We can't be too careful, or the detectives will interfere with our business. Some of the last lot were rather coarse."

"I know it, sir," answered the man addressed as Jones.

"There's nothing the matter with this," said the old man. "There isn't one person in a hundred that would suspect it was not genuine."

Jack pricked up his ears.

Looking through the crevice, he ascertained that it was a bill that the old man had in his hand.

"They're counterfeiters," he said, half audibly.

Low as the tone was, it startled Dr. Robinson.

"Ha!" said he, startled, "what's that?"

"What's what, sir?" said Jones.

"I thought I heard some one speaking."

"I didn't hear nothing, sir."

"Did you hear nothing, Ferguson?"

"No, sir."

"I suppose I was deceived, then," said the old man.

"How many bills have you there?" he resumed.

"Seventy-nine, sir."

"That's a very good day's work," said the old man, in a tone of satisfaction. "It's a paying business."

"It pays you, sir," said Jones, grumbling.

"And it shall pay you, too, my man, never fear!"

Jack had made a great discovery. He understood now the connection between Mrs. Hardwick and the old man whom he now knew not to be a physician. He was at the head of a gang of counterfeiters, and she was engaged in putting the false money into circulation.

He softly ascended the staircase, and re-entered the room he left, closing the secret door behind him.